The U.K. government is demanding action from the European Union (EU) amid strong frustration over the lack of proposals from Brussels on a post-Brexit relationship.

The U.K. is set to leave the EU in March 2019 and negotiators are working against the clock, trying to hammer a deal that will allow businesses to continue trading under relatively low tariffs. However, key differences, including the future of the Irish border with Northern Ireland, remain – leading many to believe that a no-deal is the more likely outcome.

Speaking to CNBC over the weekend, several members of the U.K. government appeared frustrated about the lack of help coming from the European Union.

"At the moment, it is very much a question of the European Union responding with its proposals. At the moment, there is nothing on the table," Chris Grayling, transport secretary told CNBC's Steve Sedgwick at the Conservative Party conference currently taking place in Birmingham.

BIRMINGHAM, ENGLAND - SEPTEMBER 30: British Prime Minister Theresa May applauds as she sits in the audience during the annual Conservative Party Conference on September 30, 2018 in Birmingham, England.

Jeff J Mitchell | Getty Images News | Getty Images

Liam Fox, trade secretary and an outspoken Brexit supporter, told CNBC on Sunday that it is the EU's "duty" to help the U.K. and put forward their proposals.

"They said they were not very happy with what the U.K. offered, in which case let them bring forward their own proposals," he said.

"Under Article 50 (the legislation that allows a EU country to leave the Union), we have the right to leave the European Union and they have a duty to help us in that future relationship. Let's see them now deliver what they promised to do in that treaty," Fox said.

But Pierre Moscovici, European commissioner for economic and financial affairs, taxation and customs, said that attacks from U.K. politicians on the bloc were unhelpful. In particular, he criticized British Foreign Secretary Jeremy Hunt's claim that the EU is like a prison in the Soviet Union.

"Leaving aside negotiations, it's just silly — if you talk to ministers coming from former Soviet bloc, it's not serious, it's propaganda, not a formula that responds to reality — whether between EU members, European countries or friends," Moscovici told CNBC's Willem Marx on Monday.

The U.K. government presented in July a plan for its future relationship with the rest of the European Union. But the latter argued that some of the proposals compromised key principles under European law.

European Council President Donald Tusk said in September that the so-called Chequers plan would not work. U.K. Prime Minister Theresa May has stood by her proposal despite such messages from the EU. She told the BBC on Sunday that her Brexit plan is not dead.

However, May also faces criticism over her plan inside her own party. Boris Johnson, the former foreign affairs minister, who is seen as a potential candidate to replace the prime minister as Conservative leader, said the Chequers plan is "deranged."

David Lidington, cabinet secretary, told CNBC on Sunday that those who criticize the prime minister need to come up with "credible" alternative proposals.

"The key thing is to get the deal with the European Union because that's what will protect jobs and the economic interests of people in this country and the integrity of the United Kingdom, Great Britain and Northern Ireland, then we go to parliament and we make the case," he said.

"I think that our parliamentary colleagues at that point will have to face up to the fact there is a real decision about this country's future to be taken, we have not yet had any credible alternative from those that are criticizing the Prime Ministers' plan," Lidington added.

Sterling and UK stocks could rally

Martin Gilbert, CEO of Standard Life Aberdeen, told CNBC's Steve Sedgwick on Monday that there could be a rally in U.K. stocks and the pound at the same time, despite their traditional inverse correlation.

When asked if both assets could rally in a scenario where Brexit happens and it is not as dramatic as some expect, Gilbert said: "Yes, definitely."

"Sterling will rally and some of the fear factor will come out of U.K. stocks," he added.